Microsoft 365 shared mailbox license requirements
In Microsoft 365, a shared mailbox does not require its own license under standard conditions. Here's the complete picture:
What's included for free
- Up to 50 GB of storage per shared mailbox
- Access by unlimited licensed users in your organization
- Send As and Send on Behalf permissions
- Access via Outlook desktop, Outlook Web App, and mobile
When a license IS required
Source: Microsoft Learn — About shared mailboxes in Microsoft 365
The key rule to remember
The mailbox is free. The users accessing it are not. Every person who needs access to a shared mailbox must have a licensed Microsoft 365 account of their own. The shared mailbox itself doesn't consume an additional license — but it also doesn't give any user free access.
Google Workspace shared mailbox license requirements
Google Workspace doesn't have a native "shared mailbox" concept identical to Microsoft 365. Instead, teams use one of two approaches:
Option 1 - Delegated Gmail account:
A Gmail account where one or more users are granted delegate access. Each delegate must have their own Google Workspace license. The delegated account itself doesn't require a separate license, but it does count against your domain's pooled storage.
Option 2 - Google Groups (Collaborative Inbox):
A Group email address that multiple members can access and reply from. Members use their existing Workspace accounts, no additional license needed for the Group itself.
Storage consideration
Google Workspace plans include pooled storage per user across the domain. Shared mailboxes (via either method) consume storage from this pool. If your organization is near its storage limit, adding shared mailboxes will accelerate consumption. Check current usage in your Admin Console.
What the license doesn't cover: the hidden limitation
Here's what most guides on shared mailbox licensing don't tell you.
Your shared mailbox is free. But once it's set up and your team starts using it, you have no visibility into how it's actually performing.
Neither Microsoft 365 nor Google Workspace shows you:
- How long your team takes to respond to emails in the shared mailbox
- Which team member is handling the majority of the workload
- How many emails have received no reply in the last 48 hours
- Whether you're meeting your response time SLA targets
- How volume trends over time
Microsoft Viva Insights tracks personal productivity data, but it doesn't monitor shared mailbox performance. Google Workspace Admin shows basic send/receive counts, but no response time data.
For a support@, sales@, or info@ mailbox handling customer or partner communication, this blind spot is significant. You might know your mailbox is free, but you don't know if it's working
How EmailMeter fills the gap
EmailMeter connects to your shared mailbox on Google Workspace or Microsoft 365 and provides the performance data that native platforms don't.
Setup takes under 5 minutes. No changes to how your team works in Outlook or Gmail.
Start tracking your shared mailbox performance for free
Shared mailbox vs. distribution list vs. Microsoft 365 Group
Teams often confuse these three options. Here's how they differ on licensing and functionality:
For a complete breakdown of when to use a shared mailbox vs a distribution list, including a decision guide and real team examples, see our dedicated guide on shared mailbox vs distribution list.
Frequently Asked Questions
Does a shared mailboxes need a license in Office 365?
No, a shared mailbox in Microsoft 365 does not require its own license for storage up to 50 GB. However, every user who accesses the shared mailbox must have a licensed Microsoft 365 account. A license is also required if the mailbox exceeds 50 GB, needs archiving, or requires litigation hold.
Does a shared mailboxes need a license in Google Workspace?
No separate license is required for a shared mailbox in Google Workspace. Whether using delegated Gmail access or a Google Groups Collaborative Inbox, members use their existing Workspace accounts. Storage consumption counts against your domain's pooled storage.
Can a shared mailbox be accessed without a license?
No. While the shared mailbox itself doesn't require a license, every user who needs to access it must have a valid license for their own account (Microsoft 365 or Google Workspace). External users cannot access a Microsoft 365 shared mailbox at all.
What happens if a shared mailbox exceeds 50 GB?
When a shared mailbox approaches 50 GB, it will first stop sending email, then eventually stop receiving email. Senders will receive a non-delivery report. To increase the limit to 100 GB, you must assign an Exchange Online Plan 2 license to the shared mailbox.
How do I track performance on a shared mailbox?
Microsoft 365 and Google Workspace don't provide native response time or SLA tracking for shared mailboxes. EmailMeter connects to your shared mailbox on either platform and tracks response times, workload distribution, and SLA compliance automatically. Start free here.
Can I enable direct sign-in to a shared mailbox in Microsoft 365?
By default, Microsoft blocks direct sign-in to shared mailboxes. If you enable sign-in, you must assign an Exchange Online license to the mailbox, otherwise it violates Microsoft's licensing terms.
